WiFi, also referred to as wireless local area network (WLAN), uses IEEE 802.11 standard technologies as its air interface. With increased network capacity and advances in communication technologies, IEEE 802.11 or WiFi systems are expected to support a larger number of stations (STAs). Accordingly, access points (APs) should be capable of handling a larger number of communication requests simultaneously, e.g., when mobile devices enter or leave the WiFi domains. For example, in a train station, when the train stops, many WiFi users that are video streaming or browsing the internet may come out from the train at the same time and try to associate with the AP in the train station to continue their video streaming or Internet browsing. In another example, multiple smart meters in a power outage area may transmit a ‘last gasp’ notification message to alert the distributor to their loss of power. After a long power outage, devices including smart meters may also try to re-associate with an AP at about the same time. In a WLAN, a communication channel can be shared by multiple STAs. However, a large number of simultaneous communications can cause collisions in the shared channel and result in a long channel access delay. An overly long access delay may cause more energy consumption in the mobile devices and jeopardize the quality of service (QoS) provisioning of different services on different STAs. Therefore, there is a need to consider QoS-aware network association in a WiFi system.